Opentk/Source/Bind/Specifications/Docs/glGetQueryObject.xml

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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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<refentry id="glGetQueryObject">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2005</year>
                <holder>Sams Publishing</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetQueryObject</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetQueryObject</refname>
        <refpurpose>return parameters of a query object</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetQueryObjectiv</function></funcdef>
                <paramdef>GLuint <parameter>id</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLint * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetQueryObjectuiv</function></funcdef>
                <paramdef>GLuint <parameter>id</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLuint * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>id</parameter></term>
            <listitem>
                <para>
                    Specifies the name of a query object.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>pname</parameter></term>
            <listitem>
                <para>
                    Specifies the symbolic name of a query object parameter.
                    Accepted values are <constant>GL_QUERY_RESULT</constant> or <constant>GL_QUERY_RESULT_AVAILABLE</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>params</parameter></term>
            <listitem>
                <para>
                    Returns the requested data.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glGetQueryObject</function> returns in <parameter>params</parameter> a selected parameter of the query object
            specified by <parameter>id</parameter>.
        </para>
        <para>
            <parameter>pname</parameter> names a specific query object parameter.  <parameter>pname</parameter> can be as follows:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_QUERY_RESULT</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the value of the query object's passed samples counter.  
                        The initial value is 0.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_QUERY_RESULT_AVAILABLE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns whether the passed samples counter is immediately available.
                        If a delay would occur waiting for the query result, <constant>GL_FALSE</constant> is returned.  
                        Otherwise, <constant>GL_TRUE</constant> is returned, which also indicates that the results of all
                        previous queries are available as well.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            If an error is generated,
            no change is made to the contents of <parameter>params</parameter>.
        </para>
        <para>
            <function>glGetQueryObject</function> implicitly flushes the GL pipeline so that any incomplete rendering
            delimited by the occlusion query completes in finite time.
        </para>
        <para>
            If multiple queries are issued using the same query object <parameter>id</parameter> before calling 
            <function>glGetQueryObject</function>, the results of the most recent query will be returned.  In this case,
            when issuing a new query, the results of the previous query are discarded.
        </para>
        <para>
            <function>glGetQueryObject</function> is available only if the GL version is 1.5 or greater.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is not an accepted value.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>id</parameter> is not the name of a query object.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>id</parameter> is the name of a currently active 
            query object.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetQueryObject</function>
            is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
            and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBeginQuery</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glEndQuery</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetQueryiv</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glIsQuery</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 2005 Addison-Wesley. 
            This material may be distributed subject to the terms and conditions set forth in 
            the Open Publication License, v 1.0, 8 June 1999.
            <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
        </para>
    </refsect1>
</refentry>